In the recent information communication technology, optical signals and electrical signals are mutually converted in conducting information communication. In such information communication, an electro-optic hybrid circuit board having both a wiring circuit board for transmitting electrical signals and an optical waveguide for transmitting light is used. As a technique for forming the conductor pattern serving as a constituent element of an electro-optic hybrid circuit board, the semi-additive method is known. (See patent document 1)
Patent Document 1: JP 2002-236228 A
In high-density information communication, there is a desire for size and thickness reductions in communication apparatus and also the electro-optic hybrid circuit boards are required to have a reduced transmission loss.
However, in forming a conductor pattern on an optical waveguide by the semi-additive method, there are cases where the resins constituting the optical waveguide degenerate due to the heat generated during sputtering, causing an increase in light transmission loss.